looking to buy a 87-88T2 diff for my FD but want to change up the final drive ratio to somewhere above 4.3:1. Are there any ring and pinion sets available for this LSD in the 4.7 range?
Rob

 

Not without very expensive custom options...
4.1:1 is standard, and there's a drop-in 4.3:1 available.


-Ted

 

There is a 4.77 rear gear and pinion available for the FD diff, but the pinion is the wrong size for FC rear end.

RX-7.com:
CL500637 4.777 Final Drive Ring and Pinion Set $772

Why are you using a FC rear end on a FD?

 

the FD torsen unit will break with my power.

-Rob

 

In that case, the long-pinion FC unit will probably also break. It's time to step up to the plate and get a competition rear end.

There is an adapter kit available that allows the older short-pinion RX-7 gear set to work in an FC differential, but I'm not sure if it can take more torque than the stock FC differential. However, the older short-pinion gear sets were available in 4.44 and 4.875, which may help in your situation. The short-pinion can also be grafted to the long-pinion shaft, which is not an uncommon modification for road race cars.

 

I'd would love to go that route but my funds have been tapped. There has been a lot of success with the 87-89 t2 units which are very simular to the KAAZ and have been labeled "bullet-proof" by the FD community. I have already purchased Labreck's diff bushings to reduce wheel hop and a diff brace is in the works. Eventually I am going to need to buy some upgraded axles as well. I am confident that the T2 LSD will hiold the power but I would preffer a higher ring and pinion ratio in order to provide more wheel torque down low.

 

I appreciate the info however and will be sure to keep that in mind.